CN105435747B - Method, adsorbent and its application of chitosan are modified using Fenton methods - Google Patents
Method, adsorbent and its application of chitosan are modified using Fenton methods Download PDFInfo
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Abstract
The invention discloses a kind of methods for modifying chitosan using Fenton methods, including：(1) chitosan is mixed with ferrous sulfate, hydrogen peroxide, water, is stirred to react completely, is separated by solid-liquid separation, obtains the chitosan sample of absorption iron ion；(2) the chitosan sample for adsorbing iron ion is mixed with glutaraldehyde, after the completion of cross-linking reaction, is separated by solid-liquid separation, obtains the chitosan absorbent of Fenton methods modification.Single crosslinked chitosan only has preferable removal effect with the processed cross-linked chitosan of hydrogen peroxide when pH value is less than 5, but when pH value is higher than 5, its removal rate can significantly decline, and the processed chitosan of Fenton methods of the present invention is regardless of under the conditions of meta-acid, still fabulous removal rate is all had in neutral conditions, common cross-linked chitosan is especially compared under neutral environment 3 times of removal rate, so the Fenton methods processing chitosan of the present invention has better pH accommodations.
Description
Technical field
The invention belongs to adsorbent preparing technical fields, are specifically related to a kind of side for modifying chitosan using Fenton methods
Method, adsorbent and its application.
Background technology
Increase with people to chemical products demand, the content of beary metal in the ecosystem constantly accumulate.And chromium is made
For heavy metal common in a kind of produce, along with plating, process hides, cement preservative, paint, pigment, weaving, steel and iron manufacturing and
The development of can industry and be largely discharged into environment.There are the chromium of three kinds of oxidation states, bivalent chromium Cr (II), trivalents in nature
Chromium Cr (III) and Cr VI Cr (VI), however only latter two is stable valence state.Cr (VI) is in contrast in soil and water body
Middle mobility is more preferable, and its toxicity, and teratogenesis, carcinogenic, mutagenesis ability is also stronger.Chromate, dichromate ion can influence to digest
Organ causes dermatitis and hand and forearm penetrating ulcer.The ceiling of Cr concentration in waste water as defined in the World Health Organization
For 0.005mg/L.
Conventionally employed Cr (VI) minimizing technology is generally chemical precipitation method, oxidation-reduction method, filtering, ion exchange, film
The methods of separation and absorption.Chemical precipitation method will produce a large amount of bed mud, and the cost of ion exchange resin and membrane separation technique
It is then relatively high.And absorption method selects space big and has not under relatively low cost since sorbing material type more
Wrong adsorption efficiency, so as a kind of research method most with application.In the selection of a variety of adsorbents, it is desirable to look for
The material high and more cheap to a kind of adsorption efficiency.Since some biomass are in the removal of heavy metal, compound and particulate matter
Aspect has good performance, this kind of compound to obtain many researchs in recent years.
Chitosan (CS) is prepared by the second largest high molecular material chitin in nature, and being one kind having bio-compatible
Property, antibacterial, degradable environment-friendly material.Contain a large amount of hydroxyl and amino in chitosan molecule, can effectively combine molten
Metal ion in liquid.In order to expand the application of chitosan in the treatment of waste water, researchers have carried out chitosan various each
The modification of sample is to improve its processing capacity, such as by chemical crosslinking, adds functional group or is for example formed by change shape solidifying
Glue bead or fiber.There are mainly two types of approach in the research to Anion-adsorption, and one is by metal-chelating, this method obtains
To product have an adsorption effect well, but while preparing, generally requires to dissolve chitosan, and preparation difficulty is made to increase.Another kind is
It handles in acid condition, in an acidic solution, most of protonated amino in chitosan molecule is made by anion exchange
With absorption heavy metal ion.But this mechanism makes the suction-operated of chitosan depend critically upon pH value of solution.As pH=6, ammonia
The sub- rate of matrix drops to 76%, and as pH ＞ 8, for amino hardly into protonation, chitosan loses the absorption to metal ion
Effect.Patent ZL201010141612.4 disclose it is a kind of chitosan surface is modified using low concentration hydrogen peroxide it is pre-
Processing method, main function mechanism be using low concentration hydrogen peroxide degradation chitosan surface amorphous chitosan molecule with
Chitosan particle surface crystalline phase constituent of chitosan is improved, to improve absorption property.The shortcoming of this method is can only be to shell
Very micro- shallow surface layer of glycan particle surface is handled.Because chitosan is that have many chitosan monomers to pass through strong hydrogen bond
Connection composition.
Invention content
The present invention provides a kind of methods for modifying chitosan using Fenton methods, and preparing adsorbent need not incite somebody to action in the process
Chitosan dissolves, and this method is simple for process, is suitable for industrialized production.
The present invention also provides a kind of Fenton methods being prepared by the above method to modify chitosan absorbent product, should
Adsorbent can significantly improve adsorption effect under neutral environment, reduce preparation and use environment and wanted to acid proof
It asks, substantially increases the practicability of adsorbent.And the mechanism of adsorbent increase adsorption capacity is not rushed with protonated amino
It is prominent, if can be used in conjunction with acid processing, moreover it is possible to further improve adsorption effect.
Containing hexavalent chromium wastewater using the modification chitosan absorbent processing of above-mentioned Fenton methods invention also provides a kind of
Application process, implementation process is simple.
A method of chitosan being modified using Fenton methods, including：
(1) chitosan is mixed with ferrous sulfate, hydrogen peroxide, water, is stirred to react completely, is separated by solid-liquid separation, obtain absorption iron
The chitosan sample of ion；
(2) the chitosan sample for adsorbing iron ion is mixed with glutaraldehyde, after the completion of cross-linking reaction, is separated by solid-liquid separation, obtains
The chitosan absorbent of Fenton methods modification.
Preferably, in step (1), the mass ratio of chitosan and ferrous sulfate is 1:(0.1~0.3), ferrous sulfate
When quality is further added by, removal rate effect no longer significantly improves, and selects the technical solution, can reduce raw material input cost.As
Further preferably, the mass ratio of the chitosan and ferrous sulfate is 1:(0.2~0.3).
Preferably, in step (1), the hydrogen peroxide uses mass percent concentration for the hydrogen peroxide of 30wt%；Work as institute
When stating the hydrogen peroxide that hydrogen peroxide uses mass percent concentration as 30wt%, the mass volume ratio of the chitosan and hydrogen peroxide
For：1：(0.1~2) (g/mL)；As further preferred, the mass volume ratio of the chitosan and hydrogen peroxide is 1：(0.2~1)
(g/mL)；Still more preferably it is：The mass volume ratio of the chitosan and hydrogen peroxide is 1：(0.2~0.5) (g/mL).
In step (1), Fenton reaction reaction rate it is very fast, preferably, it is described be stirred to react the time be 15~
120min, further preferably 30~60min.
The present invention also provides a kind of chitosan absorbents for the Fenton methods modification being prepared by any of the above-described method.
Preferably, the mass percentage content of iron atom is 0.8~1% in adsorbent.
Containing hexavalent chromium wastewater using the chitosan absorbent processing of above-mentioned Fenton methods modification the present invention also provides a kind of
Method.In actual use, directly the chitosan absorbent that the Fenton methods being prepared are modified is added to and is given up containing Cr VI
In water.
Preferably, in waste water, the content of the Cr VI is 10~500mg/L, further preferably：In waste water, institute
The content for stating Cr VI is 20~200mg/L.
Preferably, when using above-mentioned catalyst, calculated with wastewater volume, the usage amount of catalyst is (1~10) g/L；
It as further preferred, is calculated with wastewater volume, the usage amount of the catalyst is (4~8) g/L.
The adsorption mechanism of the present invention is presumed as follows：
According to existing research, chitosan to anion, including the heavy metal of anionic state absorption a main machine
Reason is that the amino after protonation generates electrostatic attraction with anion.First potassium bichromate be dissociated into aqueous solution chromic acid hydrogen radical or
Chromate, since hydrolysis generates H+, while by the protonated amino on chitosan.
It is smooth from the simple cross-linked chitosan surface of Fig. 3 a it can be seen from the figure thats first, without apparent layer structure.Fig. 3 b
For it can be seen from the figure that after the processing of Fenton methods, adsorbent surface becomes uneven.It is about the micro- of 100nm a large amount of diameters occur
Ball.The effect of Fenton methods modification has two, first, Fenton methods generate hydroxyl radical free radical, and chitosan surface is by crystalline phase and without fixed
Shape two parts form, and therefore, the hydroxyl radical free radical that Fenton methods generate can aoxidize the unformed chitosan [patent of stripping
ZL201010141612.4]；Second is that the ferric ion that Fenton methods generate, complex can be formed with chitosan.In Fig. 3 b
Microballoon may be after the reaction of Fenton methods by Fe centered on formed, it is poly- from the unformed shell of chitosan sur-face peeling
Sugar further can form beadlike polymer by join aggregation of Fe.Fig. 3 d figures are it can clearly be seen that chitosan produces after treatment
Layer structure has been given birth to, and this result is that can't see in untreated chitosan and the only chitosan of hydrogen peroxide treatment
's.This may be that Cr (VI) is absorbed into behind chitosan inside further chitosan layer structure is strutted.
Described in summary, reaction mechanism such as Fig. 7 of our releases.The oxygen radical that Fenton methods generate makes in original chitosan
A part of hydrogen bond it is disconnected, discharge the amino being difficult to be utilized originally originally inside chitosan and form new adsorption site.Together
When part Fe and the chitosan segment of interlayer be added form condensate, may play a supporting role, so as to allow Cr (VI) into
Enter inside chitosan particle, generates suction-operated.Since Cr (VI) itself is also oxidizing, the result of XPS also shows Cr (VI)
Itself can aoxidize hydroxyl makes oneself to become Cr (III), illustrates that chitosan is contacted and may also be will produce for a long time with Cr (VI)
As a result variation.Therefore, the Cr (VI) being adsorbed onto on chitosan can finally restore as Cr (III).
The adsorption effect to Cr (VI) can be effectively improved by the pretreated chitosan of Fenton methods.It is poly- with untreated shell
Sugar relatively, is obviously improved even if handling chitosan under neutral environment if the rate of adsorption and adsorption capacity of short time.
Fenton methods pre-process the functional group for not substantially changeing chitosan, but chitosan is made layer structure occur, to discharge
Originally the amino that can not be acted inside chitosan is as new adsorption site.To be fixed by Electrostatic Absorption
More Cr (VI).
Single crosslinked chitosan only has preferably with the processed cross-linked chitosan of hydrogen peroxide when pH value is less than 5
Removal effect, but pH value be higher than 5 when, removal rate can significantly decline, and the present invention Fenton methods it is processed
Chitosan still all has fabulous removal rate, especially under neutral environment in neutral conditions no matter under the conditions of meta-acid
Comparing common cross-linked chitosan has 3 times of removal rate, so the Fenton methods processing chitosan of the present invention has better pH to adapt to
Range.
Description of the drawings
Removal rate of the adsorbent that Fig. 1 is Examples 1 to 4, prepared by comparative example 1~4, comparative example 5~8 in different pH value；
FTIR spectrograms before and after the adsorbent absorption that Fig. 2 is embodiment 1, prepared by comparative example 1；
Fig. 3 is that adsorbent prepared by 50,000 times of lower embodiments 1 of stereoscan photograph adsorbs absorption prepared by front and back, comparative example 1
Scanning electron microscope (SEM) photograph before agent absorption；
Fig. 4 is SEM and the EDS figure that Fenton methods prepared by embodiment 1 handle the tangent plane edge after chitosan absorption；
Fig. 5 is the processed chitosan of Fenton methods that is prepared of embodiment 1 and comparative example 1 be prepared it is common
After cross-linked chitosan adsorbs chromium ion, the XPS spectrum figure of surface chromium existing forms；
Fig. 6 is that the common cross-linked chitosan that comparative example 1 is prepared adsorbs Fenton methods prepared by front and back and embodiment 1
The XPS spectrum figure of processed chitosan Surface Oxygen existing forms；
Fig. 7 is the reaction mechanism figure that the present invention speculates.
Specific implementation mode
Below according to embodiment, the invention will be further described：
The raw material sources used in embodiment are as follows：Chitosan (Chitosan) is purchased from the limited public affairs of Zhejiang golden shell biochemistry
Department, Deacetylation degree reach 90% or more.Glutaraldehyde (Glutaraldehyde, GLA) be purchased from Shanghai Chinese medicines group, a concentration of 25%
(w/w).Diphenylcarbazide (Diphenylcarbazide, DPCI), analysis are pure.Hydrogen peroxide (H2O2) a concentration of 30wt%,
Ferrous sulfate (Fe2SO4·7H2O), potassium bichromate (K2Cr2O7) and other reagents be analysis it is pure.
Examples 1 to 4：It is prepared by the chitosan absorbent of Fenton methods processing
Chitosan 0.5g is weighed first, is placed in triangular flask, and ferrous sulfate 0.15g, H is added2O2(0.5mL), uses distillation
Water is settled to 50mL, require the pH value for using the NaOH regulation systems of the HCl and 0.1M of 0.1M respectively to 4 according to pH value, 5,
6, to not handling sample, omit pH value set-up procedure；Magnetic agitation 500rpm stirs 1h at room temperature.5 points are centrifuged in 5000rpm
Liquid is discarded supernatant after clock, with distillation washing 3 times.
Treated chitosan is placed in triangular flask, 25% glutaraldehyde 50mL is added, at room temperature magnetic agitation
500rpm stirs 2h.Liquid is discarded supernatant after five minutes in 5000rpm centrifugations, with distillation washing 3 times.It dries, protects in 80 DEG C of baking ovens
It deposits, respectively obtains：(1) the chitosan sample of the Fenton methods processing of processing pH=4, (2) handle the Fenton methods processing of pH=5
Chitosan sample, (3) handle the chitosan sample of the Fenton methods processing of pH=6, and at (4) untreated Fenton methods
The chitosan sample of reason.
Comparative example 1~4：It is prepared by simple cross-linked chitosan adsorbent：
Directly Chitosan powder 1.0g is placed in 2.5% glutaraldehydes of 50mL, requires to use 0.1M's respectively according to pH value
The pH value of the NaOH regulation systems of HCl and 0.1M is to 4,5,6, to not handling sample, omits pH value set-up procedure, mixed liquor in
500rpm is stirred 2 hours at room temperature.Then 5000rpm centrifugations discard supernatant liquid simultaneously after five minutes, wash with distilled water after 3 times,
It is dry at 80 DEG C, it respectively obtains：(1) the simple cross-linked chitosan sample of pH=4 is handled, (2) handle the simple crosslinking shell of pH=5
Glycan samples, (3) handle the simple cross-linked chitosan sample of pH=6, and (4) untreated simple cross-linked chitosan sample.
It is prepared by the chitosan absorbent of 5~8 dioxygen water process of comparative example
Chitosan 1.0g is weighed, is placed in triangular flask, H is added2O2(0.1mL) is settled to 50mL using distilled water, according to
PH value requires that the pH value of the NaOH regulation systems of the HCl and 0.1M of 0.1M is used, to not handling sample, to save to 4,5,6 respectively
Slightly pH value set-up procedure；Magnetic agitation 500rpm stirs 1h at room temperature.Liquid is discarded supernatant after five minutes in 5000rpm centrifugations, is used
Distillation washing 3 times.
Treated chitosan is placed in triangular flask, 2.5% glutaraldehyde 50mL is added, at room temperature magnetic agitation
500rpm stirs 2h.Liquid is discarded supernatant after five minutes in 5000rpm centrifugations, with distillation washing 3 times.It is dried in 80 DEG C of baking ovens, respectively
It obtains：(1) the chitosan sample of the dioxygen water process of processing pH=4, (2) handle the chitosan sample of the dioxygen water process of pH=5
Product, (3) handle the chitosan sample of the dioxygen water process of pH=6, and the chitosan sample of (4) untreated dioxygen water process
Product.
Preparation condition influences test：
Respectively Example 1~4, comparative example 1~4, comparative example 5~8 sample 0.05g in pH be 8 10mL20mg/L
After being adsorbed 5 hours in Cr (VI) potassium dichromate aqueous solution, concentration before and after Cr (VI) is measured, calculates Cr (VI) removal rate, all samples
Product use diphenyl carbazide spectrophotometry when measuring Cr (VI) concentration, in Shimadzu UV-2401PC UV, visible light spectrophotometrics
It is measured on meter, the results are shown in Figure 1.
As shown in Figure 1, it is seen that pH be 5 and hereinafter, three kinds of chitosans (chitosan, the simple shell of Fenton methods processing are poly-
The chitosan of sugar, dioxygen water process) there is fabulous removal rate, the chitosan absorption of Fenton methods processing when pH is 6
It is with obvious effects to be better than other two.And in the case where not adjusting pH, it is lower under chitosan alone adsorption rate ratio pH=6.This be by
The non-type state on chitosan surface can be removed in hydrogen peroxide, to discharge more adsorption sites.And it is removed under acid condition
Rate rising is due to-NH2Caused by rising to anion-adsorption power after protonation.Synthesis is it can be found that Fenton methods are processed
Chitosan has fabulous removal rate in neutral conditions, and comparing common cross-linked chitosan has 3 times of a removal rate, at Fenton methods
Reason chitosan has better pH accommodations.
Embodiment 5~7：Hydrogen peroxide difference addition is tested
Respectively according to the method for embodiment 1, three gradients for not being both uniquely hydrogen peroxide addition are respectively：0.1mL、
0.5mL、1mL.After distilled water is settled to 50mL, pH to 6 is adjusted using the HCl and NaOH of 0.1M.
Embodiment 8~10：Ferrous sulfate difference addition is tested
Respectively according to the method for embodiment 1, three gradients for not being both uniquely ferrous sulfate addition are respectively：50mg、
100mg、150mg.After distilled water is settled to 50mL, pH to 6 is adjusted using the HCl and NaOH of 0.1M.
5~10 sample 0.05g of Example is adsorbed 1 hour in 10mL 200mg/L Cr (VI) solution that pH is 8 respectively
After measure.The result shows that removal rate respectively reaches 95.5%, 95.8% and 96.3% to three dosages of hydrogen peroxide from low to high.Explanation
When hydrogen peroxide has exceeded Fenton and reacted required amount, continues growing concentration and removal rate is not obviously contributed.And three
Under a difference ferrous iron dosage, removal rate is respectively 87.9%, 95.8%, 98.3%.It is removed when using 100mg ferrous sulfate
Rate obviously rises, and 150mg is significantly reduced relative to 100mg risings.Illustrate further to increase on the basis of 150mg ferrous sulfate
Add iron dosage to the help of adsorption effect also unobvious.To sum up, it is that hydrogen peroxide selects 0.1mL, ferrous sulfate choosing selecting proportioning
Use 150mg.
Embodiment 11~14：The different disposal time tests
Using the method for embodiment 1, chitosan 0.5g, hydrogen peroxide 1mL, ferrous sulfate 150mg, distilled water is settled to
50mL.PH to 6 is adjusted using the HCl and NaOH of 0.1M.It reacts 15 minutes, 30 minutes, 1 hour and 2 hours respectively.Test
When take sample 0.05g in pH be 8 10mL 200mg/L Cr (VI) solution in adsorb 1 hour after measure.
Experiment shows that processing time rose to 120 minutes adsorption rates from 15 minutes and only improves and is risen to about from about 90%
95%, illustrate that the reaction rate of Fenton reactions is very fast.But processing is still selected in order to ensure treatment effect in an experiment
120 minutes.
Structural characterization：
(1) chemical constitution characterizes
It is poly- that simple crosslinking shell prepared by front and back, comparative example 1 is adsorbed to the chitosan that Fenton methods prepared by embodiment 1 are handled
The front and back sample of sugar absorption carries out infrared detection, obtains infrared spectrum, as shown in Figure 2.In Fig. 2, line a is simple cross-linked chitosan
Infrared figure, line b are infrared figure after simple cross-linked chitosan adsorbs before absorption, line c is red before Fenton methods processing chitosan adsorbs
Outer figure, line d are that Fenton methods handle infrared figure after chitosan absorption.
Identical feature is shown by figure and data in document.In 3406cm-1The absorption band at place is since the flexible of-OH shakes
Movable property is given birth to.And it shows very wide bandwidth and then shows that hydroxyl forms hydrogen bond.In 2866cm-1The absorption band at place is stretched by C-H
Vibration generates.In 1652cm-1The absorption band at place is that amide Ⅰ causes, this absorption band is also commonly used for the meter of acetyl degree simultaneously
It calculates.And in 1554 and 1321cm-1Place is then II band of amide and Amide Ⅲ band.The apparent absorption band of other 1418,
1372 due to c h bond.In 1066,1152cm-1Place is then the stretching vibration production of the C-O keys due to primary alcohol and secondary alcohol respectively
It is raw.
As can be seen that in 1066,1152cm-1The peak position of place's primary alcohol and secondary alcohol can see simple cross-linked chitosan
The peak peak area is significantly greater than before absorption adsorb after and Fenton methods treated chitosan, and in 1700cm-1Above simultaneously
Apparent peak is not seen, it is not because being oxidized to aldehyde or acid to illustrate that the peak area of alcoholic extract hydroxyl group substantially reduces main cause.And
Hydrogen bond can be such that group bond force constant reduces, and absorption band broadens, and intensity increases.So hydrogen bond is answered before simple cross-linked chitosan absorption
This is obviously more than after the processing of Fenton method.
(2) surface texture and Elemental redistribution
In Fig. 3, (a) is that the scanning electron microscope (SEM) photograph (b) of simple cross-linked chitosan under 50,000 times is that Fenton methods processing chitosan is inhaled
Scanning electron microscope (SEM) photograph (c) before attached is that the scanning electron microscope (SEM) photograph (d) after the processing chitosan absorption of Fenton methods is 1500 times of lower Fenton
Method handles the scanning electron microscope (SEM) photograph after chitosan absorption.
The chitosan scanning electron microscopic picture of simple cross-linked chitosan and the processing of Fenton methods is shown in Fig. 3.From Fig. 3
(a) figure can be seen that simple cross-linked chitosan surface is smooth, without apparent layer structure.(b) it can be seen from the figure that exists in Fig. 3
After the processing of Fenton methods, adsorbent surface becomes uneven.There is the microballoon that a large amount of diameters are about 100nm.These microballoons can
It can be formed centered on after Fenton methods are reacted by Fe.Since Fe and chitosan can form complex, and it is unformed
Chitosan from chitosan sur-face peeling, then can be formed further using Fe as join aggregation spherical poly- under the effect of excessive hydrogen peroxide
It is fit.And (c) figure is photo of the processed chitosan of Fenton methods after absorption Cr (VI) in Fig. 3, it can be seen that same
Under 50,000 times, chitosan surface is more coarse than simple cross-linked chitosan surface, but protrusion compared to Fenton methods processing after when want
Small is more, can't see apparent glomerate aggregation, but more dense.And (d) figure is Fenton methods processing absorption Cr in Fig. 3
(VI) photo after under 1500 times, top plane is the section that knife is cut out.
It can be seen that apparent layer structure, about 1 μm or so of every layer of thickness is presented in the chitosan in picture.
Shown in table 1 constituent content analysis of the Cr (VI) on its section is adsorbed for chitosan after EDS scan process.Wherein
C and O come from chitosan.It is to introduce that K, which is due to the use of potassium bichromate,.Fe be Fenton reaction when deposit on chitosan, and
Cr be inhaled it is appended.Wherein Fe and Cr mass percents are respectively 2.25 and 12.17.Fe atomic weight is 55.85, Cr 52,
So the ratio between amount of substance on chitosan section of Fe and Cr is about 1:5.8.
X-ray energy spectrum after the chitosan absorbent absorption chromium ion of 1 Fenton methods of table processing analyzes data
Fig. 4 is the photo for the tangent plane edge that Fenton methods prepared by embodiment 1 are handled after chitosan absorption, and top is absorption
The side of agent, lower section are sections.Wherein a figures are SEM figures, and b figures are EDS figures.B figures are scanned using X-ray energy spectrum in a figures position
Mapping afterwards.
The detectable depth of EDS is about 5 μm or so, i.e., about 3 to 4 layers element overlaid is shown in EDS layered images
As a result.It can be found that Fe focuses primarily upon the surface of adsorbent in EDS layered images, upper left corner distribution is more in figure, and
It is then distributed on the inside of adsorbent less and loose.And Cr is different, has a large amount of distributions in adsorbent surface and inside, and deeply
There is no the signs of decaying on the scale that 10 μm of surface.It is mainly in combination with the table in chitosan that this, which just illustrates that Fe is reacted in Fenton,
Face, and internal only presence on a small quantity.And Cr can go deep into chitosan in adsorption process along gap between layers
Inside can finally be adsorbed in the inside of chitosan.
(3) reduction of Cr (VI)
The existing forms of XPS primary display surface elements.Fig. 5 is that the Fenton methods that embodiment 1 is prepared are processed
Chitosan (a in figure)), comparative example 1 be prepared common cross-linked chitosan absorption chromium ion rear surface chromium existing forms XPS
Spectrogram (b in figure)).As can be seen from Figure 5, when adsorbing Cr (VI) of 100mg/g, either the processed shell of Fenton methods is poly-
Sugared or common cross-linked chitosan is shown in the peak at 576.4 and 586.1eV, that is, represents the peak of Cr (III) than 578.0 Hes
Want high in the peak that the peak-of 587.2eV represents Cr (VI).No matter illustrating whether chitosan is processed by Fenton, in the concentration
Lower Cr (VI) can rely on the oxidability of itself to make itself to be largely reduced into Cr (III).In addition may be used also in both figures
The peak area of Cr (III) is obviously big after chitosan absorption to find the processing of Fenton methods, and since XPS same elements are different
The ratio between form peak area is identical as the ratio between the amount of substance, so can also draw a conclusion, in the processed chitosan of Fenton methods
Upper more Cr (VI) will be reduced.
In order to find the electron donor in Cr (VI) reduction process, we are detected the form of Surface Oxygen, such as Fig. 6 institutes
Show, the form spectrogram for common cross-linked chitosan adsorbent Adsorption of Chromium front surface oxygen a) being prepared for comparative example 1 in figure, b) be
The form spectrogram for the common cross-linked chitosan adsorbent Adsorption of Chromium rear surface oxygen that comparative example 1 is prepared, c) standby for embodiment 1
Before the chitosan Adsorption of Chromium for the Fenton methods processing arrived.As can be seen that in 529.7eV generations before the absorption of common cross-linked chitosan
The peak position that epoxy is combined with metal is hardly visible peak.And in Fenton methods, treated that chitosan then has obviously before absorption
Peak, illustrate that the oxygen Yu Fe on surface in Fenton method processing procedures have combination.In addition the chitosan surface before common crosslinking absorption
There is the peak of part C=O keys, this is because also being carried caused by the acetyl group of part on chitosan.And common cross-linked chitosan is adsorbing
After Cr (VI), the peaks C=O obviously increase, this can illustrate that the electron donor restored in Cr (VI) is exactly oxygen.In addition in Fenton methods
Treated, and chitosan surface C=peaks O also obviously increase, because Fenton reactions inherently oxidation reaction, this explanation exist
After Fenton reactions ,-the O-H on surface has part to be oxidized into C=O.
Claims (3)
1. a kind of handling the method containing hexavalent chromium wastewater using chitosan absorbent, which is characterized in that the chitosan absorbent
For the chitosan absorbent of Fenton methods modification；
The chitosan absorbent of the Fenton methods modification is prepared by the method for modifying chitosan using Fenton methods, described
Include using the method that Fenton methods modify chitosan：
(1) chitosan is mixed with ferrous sulfate, hydrogen peroxide, water, is stirred to react completely, is separated by solid-liquid separation, obtain absorption iron ion
Chitosan sample；
(2) the chitosan sample for adsorbing iron ion is mixed with glutaraldehyde, after the completion of cross-linking reaction, is separated by solid-liquid separation, obtains
The chitosan absorbent of Fenton methods modification.
2. according to claim 1 handle the method containing hexavalent chromium wastewater using chitosan absorbent, which is characterized in that useless
The content of Cr VI described in water is 10~500mg/L.
3. according to claim 1 handle the method containing hexavalent chromium wastewater using chitosan absorbent, which is characterized in that with
Wastewater volume calculates, and the usage amount of catalyst is (1~10) g/L.
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| CN1473856A (en) * | 2002-08-08 | 2004-02-11 | 青岛海洋大学 | Process for preparing low molecular chitosan |
| CN102079795A (en) * | 2009-11-27 | 2011-06-01 | 中国人民解放军第二炮兵总医院 | Preparation of water-soluble crosslinked chitosan and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1473856A (en) * | 2002-08-08 | 2004-02-11 | 青岛海洋大学 | Process for preparing low molecular chitosan |
| CN102079795A (en) * | 2009-11-27 | 2011-06-01 | 中国人民解放军第二炮兵总医院 | Preparation of water-soluble crosslinked chitosan and application thereof |
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